A 1×N type Small Form Factor (SFF) connector, such as the conventional 1×N type QSFP+ connector shown in FIGS. 1a and 1b or any one of other SFF connectors, typically includes a male optical module. The conventional male optical module A generates between 1.0-4.0 watt power and heat in use. According to heat dissipation requirements on the male optical module A, as shown in FIG. 1a, an independent heat sink 20 is positioned on each module receiving port 11 in a 1×N type housing 10. After the male optical module A is inserted into the housing 10, a bottom of the heat sink 20 contacts a top surface of the male optical module A, and the heat generated by the male optical module A is radiated into air through the heat sink, thereby reducing the temperature of the male optical module A, thus maintaining the normal operation of the male optical module A.
In the conventional male optical module A shown in FIG. 1b, the adjacent heat sinks 20 do not contact each other, and an air gap d1 approximately equal to 0.5 mm is formed therebetween. Each independent heat sink 20 is positioned on the 1×N type housing 10 by a heat sink clamp 12 (see FIG. 1a).
As shoon in FIG. 1c, a boss 21 is formed on a bottom of each heat sink 20. The bottom of the boss 21 contacts the male optical module A. Since the independent heat sink clamp 12 is positioned, the heat sink 20 can tightly contact the male optical module A regardless of height tolerance of the boss 21 and size tolerance of the male optical module A.
The SFF connector may be mounted in a case of a customer device, and inputs an optical signal to the customer device through the male optical module. A corresponding female optical module (e.g. housing 10) receives the optical signal and transmits the received optical signal to other members in the case. In the design of the case of customer device, however, an airflow in a left-right direction DI shown in FIG. 1a is generally adopted to perform heat dissipation.
In the design shown in FIG. 1a, the 1×N type QSFP+ connector comprises a heat sink array of 1×N in the airflow direction DI. However, airflow resistance exists between the heat sink fins. Thus, when the airflow in the airflow direction DI flows through the first and the second columns of heat sinks 20 in the heat sink array of 1×N, the airflow escapes from between the heat sinks 20, and flows toward the upper, the front, and the rear portions where it is not blocked by fins. As a result, the columns of heat sinks further downstream of the heat sink array 20 of 1×N can not be effectively cooled by the airflow.
In addition, in order to permit a light guide pipe 30 (see FIG. 1a) to pass through the heat sink 20, the existing heat sink 20 is generally designed in a pin form. The heat sink 20 has a height no larger than ⅓ of a height of the light guide pipe 30, resulting in the light guide pipe 30 preventing the airflow from flowing through the heat sink 20 because of the presence of the light guide pipe 30. As a result, the light guide pipe 30 further reduces airflow to the last columns of heat sinks 20 in the heat sink array 20.
Furthermore, since of the heat sinks are independent from each other, and the air in the gap between the heat sinks has a very low thermal conductivity (about 0.02 w/mk), the gap d1 cannot effectively form heat convection and essentially acts as a heat insulation between two adjacent heat sinks 20. As a result, heat cannot be transferred between adjacent heat sinks 20 efficiently. Consequently, the last columns of heat sinks 20 in the airflow direction DI have a temperature higher than that of the first column of heat sink by about 10-20° C., depending on actual working condition. Generally, the last two columns of heat sinks in the airflow direction have the highest temperature, and empirically, the male optical modules A corresponding to the last two columns of heat sinks 20 in the airflow direction DI are also conventionally known to be most likely to fail during use.
Therefore, there is an industry need for a SFF connector that overcomes or alleviates the heat dissipation problems discussed above for convention SFF connectors.
The use of a monolithic heat sink, rather than plurality of independent heat sinks, would alleviate some of the heat dissipation problems discussed above. However, the use of a monolithic heat sink directly positioned on an optical module presents a number of challenges and drawbacks.
For example, as shown in FIG. 14, a monolithic heat sink 20′ is positioned in direct, thermal contact with an optical module A. A protruding step is positioned at each port of the optical module A in a bottom of a heat sink 20′, with each protruding step thermally contacting the optical module A to dissipate the heat. The problem with such an approach is that a height of a boss 21 on the bottom of the heat sink 20′ and a size of the optical module A both have manufacturing tolerances. If the optical module A with an upper tolerance limit mates with the boss 21 with an upper tolerance limit, the heat sink 20′ may be raised in a height direction. For example, the middle optical module A shown in FIG. 14 raises the heat sink 20′ in the height direction. As a result, a gap is produced between the other optical modules A with a tolerance below the upper tolerance limit and the boss 21 on the bottom of the heat sink 20′. This gap prevents the other optical modules with the tolerance below the upper tolerance limit from thermally contacting the boss 21 on the bottom of the heat sink 20′. Therefore, the right and the left optical modules A shown in FIG. 14 cannot contact the boss 21 on the bottom of the heat sink 20′. Thus, the use of a monolithic heat sink in direct contact with the optical module A shown in FIG. 14 fails in actual application.